L10 - Anatomy of the knee Flashcards
KNEE JOINT
i) which two bones is it an articulation between? which bone is not included?
ii) where is there a second articulation between?
iii) what type of joint is it?
iv) which movements occur here? (3)
v) label diagram
i) distal femur and proximal tibia (not fib)
ii) second articulation between femur and patella
iii) synoival bicondylar hinge joint
iv) extension, flexion and some rotation when partially flexed
v) A - patella, B - medial epicondyle of femur, C - tibia
FUNCTIONS OF THE KNEE
i) what are the two main functions?
ii) what is unsual about this? what does this therefore cause
iii) name three bony factors strengthening the knee joint
iv) same three soft tissue factors strengthening the knee joint
i) weight bearing when standing and mobility
ii) usually these two functions are incompatible therefore the knee is frequently injured
iii) bony expansions of femur and tibia, locking mechanism when limb is extended, femoral angle
iv) ligaments, menisci and muscles
BONY EXPANSIONS
i) what is the role?
ii) name two bony expansions on the femur
iii) name the bony expansion on the tibia? what do these form? what does this articulate with?
iv) label diagram
i) provide a stable base for bipedalmism
ii) femoral condyles and epicondyles
iii) tibial condyles = tibial plateau > artic w femoral condyles
iv) A - femoral condyles, B - epicondyles, C - tibial condyles,
D - intercondylar fossa
LOCKING MECHANISM
i) what is the role of this mechanism?
ii) what three factors contribute to the locking mechanism?
iii) explain each mechanism
i) reduces amount of energy required when extended
ii) 1) shape of femur - femoral surfaces are round in flexiona nd flat in extension
2) rotation - medial rotation of the femur on the tibia in extension - tightens the ligaments of the knee and locks it in place
3) centre of gravity - COG in front of knee when standing straight maintains extension
FEMORAL ANGLE
i) what position of the femur allows the knee joint to sit directly below the pelvis?
ii) what occurs during development to allow this to happen?
iii) which two axis is the femoral angle between? what is the name of the angle? approx how many degrees is it?
iv) how can these two axis be drawn in the clinic?
i) slightly adducted femur
ii) medial rotation during development
iii) anatomical axis and the mechanical axis
- Q angle is approx 15 degrees
iv) anatomical axis - ASIS > tibial tuberosity
mechanical axis - line straight through fem head, centre patella
KNEE DEFORMITIES - VARUS
i) what is it a deformity of?
ii) in which direction is the tibia displaced?
iii) who is it common in? (2)
iv) what does it cause the knees to do? how is the Q angle affected?
v) what can it eventually lead to?
i) deformity of angle between femur and tibia
ii) tibia is displaced medially
iii) common in children under 2 when learning to walk and those with rickets
iv) causes knees to be pushed apart > decrease in Q angle
v) increased stress on medial condyles can result in joint degeneration
KNEE DEFORMITY - VALGUS
i) which way is the tibia displaced?
ii) who is it common in? (3)
iii) what happens to the knees? what happens to the Q angle?
iv) what can it eventually lead to?
i) tibia displaced laterally
ii) most common in children 2-4, rickets and arthritis
iii) knee knock together and Q angle gets bigger
iv) stress on lat condyles of tib and femur can lead to joint degeneration
which knee deformity is depicted in A and B?
how does the Q angle change in each?
A - varus (decreased Q angle)
B - valgus (increased Q angle)
LIGAMENTS OF THE KNEE
i) what do they provide?
ii) name the two extracapsular ligaments
iii) name the two intracapsular ligaments
i) provide stability
ii) extracap - medial and lateral collateral ligaments
iii) intracap - ant cruciate and post cruciate
LATERAL COLLATERAL LIGAMENT
i) what is it aka?
ii) what is its shape and character? what does it prevent?
iii) which structures does it run from and to?
iv) is it common or rare to tear the LCL? what deformity occurs if it us torn? how is the Q angle affected?
i) aka fibular collateral ligament
ii) strong round cord that prevents medial displacement of the tibia
iii) runs from lateral epicondyle of femur to the fibular head
iv) rare to tear
- tearing causes varus deformity due to med displac of tib
- decreased Q angle
MEDIAL COLLATERAL LIGAMENT
i) what is it aka?
ii) what is its shape and character? what does it prevent?
iii) which structure does it run from and to?
iv) what is it directly attached to?
v) is it rare or common to tear the MCL? if torn what type of deformity does it cause? how is the Q angle affected?
i) aka tibial collateral ligament
ii) broad flat band that prevents lateral displacement of the tibia
iii) runs from med epicondyle of the femur to the tibia
iv) direct att to the medial meniscus
v) common to tear > causes valgus deformity and inc Q angle
INTRACAPSULAR LIGAMENTS
i) what is the anterior cruciate lig anterior in relation to? what is the posterior cruciate lig posterior to?
ii) what is the function of each cruiciate ligament? what state is one of the ligaments always in?
iii) where does the PCL pass (3) where does the ACL pass (3)
iv) what effect does medial rotation of the leg have on the ligaments? what does this limit?
v) what effect does lateral rotation have on the ligaments? what does this allow?
i) ACL is anterior in relation to the tibia and PCL is posterior in relation to the tibia
ii) ACL - prevents anterior displac of tibia on femur
PCL - prevents posterior displac of tibia on femur
iii) PCL passes up, forward and medial
ACL psases up, backward and lateral
iv) medial rot of leg tightens the ligaments and limits rotation
v) lateral rotation of the leg unwinds the ligaments to increase rotation
label the ligaments in the diagram
A - anterior cruciate
B - posterior cruciate
C - lateral collateral
D - medial collateral
ANTERIOR CRUCIATE LIGAMENT
i) is it strong or weak? what situaiton is it injured in?
ii) what action causes injury?
iii) what clinical test can be performed to test the ACL? how is the knee positioned? what bone is moved? what bone maintains in position?
iv) what sign is seen if there is an ACL injury in the above test?
i) weak - commonly injured in sports injury
ii) sudden twisting of the knee > rupture ACL
iii) Lachman test
- knee is slightly flexed
- move the tibia but keep femur still
iv) laxity during the maneovre indicates ACL injury
POSTERIOR CRUCIATE LIGAMENT
i) is it commly injured?
ii) what is its main role? what situation is this utilised in?
i) stronger so rarely injured
ii) main role of stabilisation of knee when flexed eg when walking down a hill
MENISCI OF JOINT
i) what are they? name three roles
ii) which of the menisci is smaller? which one attaches to its adjacent collateral ligament?
iii) where do the menisci attach to?
iv) which meniscus is more mobile? why?
v) label diagram
i) crescent shaped plates of fibrocartilage
ii) lateral is smaller and more circular
- medial meniscus is larger and attaches to the MCL
iii) menisci attach to intercondylar areas of tibia
iv) lateral meniscus is more mobile than medial as medial attaches to MCL
v) A - lateral meniscus, B - medial meniscus, C - ACL, D - PCL
QUADRICEPS FEMORIS
i) what action does it have on the leg? what does it also do?
ii) name the four heads? which one is also a flexor of the thigh?
iii) label the diagram
iv) which fibres of which muscle prevent lateral displacement of the patella due to an adducted femur?
i) extends the leg and stabilises the knee
ii) rectus femoris (flexes thigh), vastus lateralis, vastus medialis, vastus intermedius
iii) A - v. medialis, B - v. intermedius, C - v. lateralis, D - rectus femoris
iv) oblique fibres of vastus medialis prev lat displac of patella
EXTENSOR MECHANISM
i) which three things make up the extensor mechanism?
ii) what is the medial and lateral patella retinaculum? which two muscles does it come from? what is its role?
iii) what type of bone is the patella? what role does it play? which bone does its posterior surface articulate with?
iv) label diagram
i) quadriceps tendon, patella and patella ligament
ii) med and lat patella retinaculum are apneurotic expansions of vastus lateralis and medialis
- help to stabilise the patella
iii) patella is a sesamoid bone
- protects quad tendon from stress during locomotion
- smooth oval facet on post surface artic with femur
iv) A - quad tendon, B - patella, C - patella ligament,
D - lat patella retinaculum, E - medial patella retinaculum
FLEXORS OF THE LEG
i) which two muscles flex the leg? which group also med/lat rotates the leg when flexed?
ii) which three muscles make up the hamstrings? where do all these muscles originate from? which muscle is the exception?
iii) label the diagram
i) hamstrings and gastrocnemius
hamstrings also med/lat rot when the leg is flexed
ii) hamstrings = biceps femoris, semimem and semiten
- all orig from the ischial tuberosity apart from short head of biceps fem (comes from femur)
iii) A - semitendinosis, B - semimembranosus, C - biceps femoris
UNLOCKING OF THE EXTENDED LEG
i) which muscle unlocks the knee joint? what action does it have on the femur when the foot is on the ground?
ii) what does this action have on the ligaments?
iii) where does this muscle originate? which area does this muscle pass through? which ligament does it pass under? where does it insert?
iv) which muscle is depicted in the diagram?
i) popliteus unlocks knee joint
- laterally rotates femur on tibia when foot is on the ground
ii) loosens the ligaments that traverse the knee
iii) orig from the tibia and passes through the joint capsule
- passes under the lateral collat lig to insert into lat condyle of femur
iv) popliteus
